1. Field of the Invention
The present invention relates to a technical field of pressing heat-softened material to mold an optical component using a mold divided into a first mold (an upper mold) and a second mold (a lower mold) which face each other, more specifically, a mold for an optical component to achieve a molding process with high accuracy.
2. Description of the Related Art
In recent years, a highly accurate molding process is required for an optical lens (an optical component) with advanced functions has been developed. Therefore, studies of molding techniques are promoted to meet the requirement. In particular, to mold an optical lens, a technology for highly accurately centering a mold (a first mold and a second mold) which is repeatedly closed and opened is one of essential molding technologies.
Here, to center a mold means to align rotational symmetry axes of the first mold (the lower mold) which molds a lens surface of the optical lens and the second mold (the upper mold) which molds the other lens surface of the optical lens in a state where the mold is closed.
To achieve centering of a mold with high accuracy, conventionally, a mold for an optical lens is well-known in which a plurality of rolling objects are cylindrically arranged, and in which side surfaces of a lower mold and an upper mold are inscribed with the cylindrically arranged rolling objects. In this structure, both of the lower mold and the upper mold are centered coaxially by the rolling objects and relatively move along rotational symmetry axes of the both in a state where the rotational symmetry axes are identical with each other. Therefore, the mold for the optical lens can be repeatedly closed and opened in a state where the lower mold and the upper mold are centered (See JP2004-262734A).